In recent decades a major impulse has been given to the introduction of advanced composite materials in the aeronautical industry, replacing the aluminum alloys in the manufacture of large primary structures of commercial aircraft: lifting surfaces (wings and stabilizers) and fuselage.
These composite material structures do not differ greatly from their metal predecessors: covers or skins formed from two-dimensional panels (commonly known as skins), stiffened by means of beam type elements (stringers), and in turn supported by structural elements that maintain the geometry of these panels and provide the structure with overall rigidity: ring-frames in the case of fuselages and spars and ribs in the case of lifting surfaces.
This intensive introduction of composite materials has been possible thanks to improvements in the techniques and devices for automatic stacking and cutting of laminates obtained from belts consisting of reinforcement fibers preimpregnated with polymer resins and, in recent years, to improvements in the techniques of automatic forming and positioning of stringers. Nevertheless, there still exists a very high percentage of manual operations associated both with the process of joining the stringers and with the placement and removal of the tools associated with them.
There exist various manufacturing processes with composite material for achieving the joining of all the parts making up a stiffened cover. The most notable are: co-curing, co-bonding and secondary bonding. The chosen process influences the mechanical characteristics, the manufacturing costs and the geometric characteristics.
Co-curing is done with the two components fresh, in such a way that the two are effectively cured together in order to form a single piece. It has a very good structural behavior and is carried out in a single curing cycle, but very complex tools are needed in order to be able to do this.
Co-bonding uses an adhesive to join the cured component and the fresh component during the curing cycle of the fresh component. It presents a very good structural behavior and less complex tools than in the previous case, but it has the drawback that two curing cycles need to be used.
Secondary bonding also uses an adhesive, but in this case for joining two previously cured components. It presents a good structural behavior and the manufactured pieces can be stored without any special conditions, but it too needs two curing cycles.
In this case the proposed solution is applied in a co-bonding process since the tools in this case are simpler, but the applicability of the invention depends on the tools, not on the type of process.
The general stages of the manufacturing process for a composite material component are: preparation of the tools, laying the fiber, cutting, hot forming, preparation of the vacuum bag, polymerization in autoclave, removing from the mold, trimming and inspection.
So far, the positioning, handling and assembling process for tools has been mainly carried out manually since its automation was fairly complex on account of the configuration and shape of the tools used in the manufacture of carbon fiber parts. The tools used here and also the system that is advocated permits these operations to be automated in addition to ensuring the correct manufacture of the part.
The system prevents any delaminations occurring when the tool is removed, it places (or removes as appropriate) the tool properly thanks to the optical positioning system and it ensures the correct placement of a tool with respect to the attached tool piece.